FMF - Friends of Minerals Forum, discussion and message board

[Ifoundsomething]

I need help identifying a very unusual stone, for Indiana anyway . I was fishing today and this caught my eye I have never seen anything like this.
Any information you can provide I would appreciate.

[Ifoundsomething]

Was fishing in Indiana and this caught my eye. I have never seen anything like this. Please help. Btw it is non magnetic.

[Glen Miller]

When asking for an identification, please include as much information on where you found it, the size, and local geology that you may know. Think of what you'd like to know about the piece if someone asked you to identify it.
And, I'm not going to guess about what rock/mineral that is.

[Ifoundsomething]

I believe it's black garnet. What info would be helpful? I found it on a creek that was recently flooded. It's in park county Indiana along the Walbash River. The area has a lot of shale and coal. I have more pictures I can send via email. I had a hell of a time just putting up the one pic.

[alfredo]

Black garnet is very unlikely in Indiana.... wrong geological environment.

It is more likely sphalerite (a zinc ore) or oxidized pyrite. Find a piece of broken porcelain and rub the rough surface over a corner of those black crystals. That will grind a tiny bit off and tell you what color the powder is. The powder color will help identify it.

[James]

So, please do item 7 on this page:

http://www.mineral-forum.com/message-board/viewtopic.php?p=19487#19487

Also check hardness (item 8).

If the streak is yellow and the hardness is 3.5-4 then it may well be sphalerite. Garnet would be much harder and the streak would be red.

[Bob Harman]

Your photos are not so good and the specimen could use a good cleaning which might make identification easier. Put the example in soapy water with household bleach overnight. Then take a toothbrush and scrub the areas vigorously. Finally, follow with a strong rinse water stream.

Despite the fact that it was found in Parke County, away from most geode sites, some odd similar finds are made in that area. West-central Indiana, near the Illinois border, hosts several small stream areas with geodes. This find may fit one of these examples. Much of the Northern 2/3 of the state is covered with glacial till with scattered erratics. SE Indiana is ordovician, South-central Indiana (where geodes occur) extending to West-central Indiana is mid mississippian age and Southwest Indiana (where coal and oil occur) is pennsylvanian age. BTW it is PARKE COUNTY and WABASH RIVER.

Anyway, I believe you have found a long broken fragment of an Indiana geode, or a broken portion of a void with druzy quartz. The blackish crystals are not garnet and do not look like any sphalerite that I have ever seen. Look carefully at both photos, especially the top area of both, especially where the "rind" grades into the dark crystals in the ? cavity. The resistant rind is quartz grading into the dark crystal tips suggesting iron stained druzy quartz tips with many chips and dings. Not sphalerite to me as there is the graduation rather than 2 adjacent but distinctly separate minerals. The dark blackish color doesn't bother me as I have many examples of all colors of iron staining in long opened deteriorating geode fragments. All very common. BOB

[alfredo]

On second thoughts, I agree with Bob: stained quartz is more likely.

[Ifoundsomething]

It doesn't look like a geode.

[Riccardo Modanesi]

Hi to everybody!
Let me launch an adventure of mine: SCHORLITE! Why not? Had anybody chscked the streak colour or the hardness of these crystals?
Greetings from Italy by Riccardo.

[Ifoundsomething]

I will try to send more pics.

[Ifoundsomething]

Another.

[Ifoundsomething]

Notice the white.

[Bob Harman]

A couple of additional points.
From the original pics, the GRADATION seems important. It appears to all be 1 mineral, from the grayish edges to the dark crystal tips toward the center of the example.
Point #2: Indiana is sedimentary with relatively few simple minerals native to the state and these are sedimentary. Other than micro minerals and a few sparsely occurring very small examples of other minerals, there is not much. Some may mention other minerals, but most will not be found or ever reported in the state. The geology is just not right. I suppose, if from a glacial erratic, all bets are off, but unlikely.

In the coal areas of SW Indiana there are reports of dark druzy quartz lining voids of replaced wood from the tropical forests of the Pennsylvanian age. The additional photos suggest this. An irregular piece of petrified wood with druzy quartz lining a void. But, never-the-less still quartz. BOB

[Bob Carnein]

The northern to-thirds of Indiana is glaciated, so I wouldn't worry too much about whether the minerals in this specimen came from Indiana. That said, it could be almost anything, without better photos and data on physical properties.

[Matt_Zukowski]

We have an old coal mine around here with rocks that look just like your picture, although the pictures make it hard to be sure of anything. Some of the rubble around the mine is rocks containing thin and dirty (meaning sediment rich, coal poor) coal layers. Is there any way this is a little coal seam in a sandstone?

I think we should stop trying to guess until this guy gives us more info. A key thing to do is test the hardness. I would add, can you break off the black stuff? If you can break off the black stuff, can you crush it with light taps from a hammer? Can you drag the fragments across paper and leave a streak?

You can demonstrate your desperation by reading our guidance on asking "What is it" questions and provide more info as has already been suggested.

[James]

As I said before, please do item 7 on this page:

http://www.mineral-forum.com/message-board/viewtopic.php?p=19487#19487

Also check hardness (item 8).